diff mbox

[1/2] Fix cross vendor migration issue with unusable bit

Message ID 1240915530-3995-1-git-send-email-andre.przywara@amd.com (mailing list archive)
State New, archived
Headers show

Commit Message

Andre Przywara April 28, 2009, 10:45 a.m. UTC 
AMDs VMCB does not have an explicit unusable segment descriptor field,
so we emulate it by using "not present". This has to be setup before
the fixups, because this field is used there.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
---
 arch/x86/kvm/svm.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

Avi, pleasy push this patch also to 2.6.30, since it fixes a bug introduced
in 2.6.30-rc1.

Thanks,
Andre.

Comments

Avi Kivity May 4, 2009, 9:28 a.m. UTC | #1 
Andre Przywara wrote:
> AMDs VMCB does not have an explicit unusable segment descriptor field,
> so we emulate it by using "not present". This has to be setup before
> the fixups, because this field is used there.
>
>   

Applied both, thanks.
diff mbox

Patch

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 1821c20..1580464 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -796,6 +796,11 @@  static void svm_get_segment(struct kvm_vcpu *vcpu,
 	var->db = (s->attrib >> SVM_SELECTOR_DB_SHIFT) & 1;
 	var->g = (s->attrib >> SVM_SELECTOR_G_SHIFT) & 1;
 
+	/* AMD's VMCB does not have an explicit unusable field, so emulate it
+	 * for cross vendor migration purposes by "not present"
+	 */
+	var->unusable = !var->present || (var->type == 0);
+	
 	switch (seg) {
 	case VCPU_SREG_CS:
 		/*
@@ -827,8 +832,6 @@  static void svm_get_segment(struct kvm_vcpu *vcpu,
 			var->type |= 0x1;
 		break;
 	}
-
-	var->unusable = !var->present;
 }
 
 static int svm_get_cpl(struct kvm_vcpu *vcpu)